Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Anand Prakash

Abstract

Transesterification of vegetable oil to biodiesel is a multistep process affected by mass transfer, mixing and chemical reaction equilibrium. Attempts have been made in this study to overcome these limitations by gradually feeding oil into a pool of alcohol. This approach provided large excess of alcohol to allow reaction to proceed further as well as allowed easy dispersion of oil into the alcohol. As a result improved conversion of feed, higher yield and better product quality were achieved. Comparisons have been made with other methods to show the differences and highlight improvements. Reactions were conducted at various reaction conditions for transesterification of canola oil with both methanol and ethanol using potassium hydroxide as a base catalyst. Reaction progress was followed by analysing samples collected at regular intervals from one liter reactor using Gas Chromatography Technique. The quality and yield of biodiesel obtained with the gradually fed method (G-Fed Method) were significantly improved ¸¸compared to conventional method. Detailed comparison studies are included for methanolysis and ethanolysis in G-Fed method. Methanolysis gives better yield over ethanolysis in G-Fed method. In addition kinetic studies have been conducted in detail and a kinetic model is developed to predict reaction rate constants of the transesterification reaction in batch as well as G-Fed method. The kinetic model following second order was used to determine the kinetics of canola oil in ethanolysis reaction at different temperature in batch runs. For the kinetic study of G-Fed method appropriate reaction rate equations are formulated including the mass transfer effects for different cases of order of reaction. Methanolysis and ethanolysis in G-fed method follow pseudo first order with higher rate constant with methanol.

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